This study evaluates a novel application of simulation to transitioning healthcare practices. Process gaps created by systems in flux are identified through immersive multidisciplinary scenarios followed by facilitated debriefing. This premise may be recursively tested where industry trends drive configured change in complex healthcare delivery systems. Neonatal Intensive Care Units (NICU) have shifted towards single family room design, given descriptive reports on benefits for family privacy, patient environment, and staff communication. Hospital staff preparation for the marked culture change is conspicuously scarce in the literature. Prior to opening the nation's largest single family room NICU in 2009, Women & Infants Hospital (WIHRI) developed TESTPILOT: Transportable Enhanced Simulation Technologies for Pre-Implementation Limited Operations Testing. We modeled a functional, immersive, in situ single family room NICU, with the explicit focus of enhancing patient safety at transition. Simulation-based exploration identified 164 latent safety threats (LST) and inefficiencies without exposing a single neonate to risk. Practical changes were made to a) verbal and written communication protocols, b) admissions workflows, c) rapid team responses, d) family centered care e) scripting, f) facilities, g) supplies and equipment, and h) staffing and training issues. Many of these had not been anticipated prior to TESTPILOT, most notably the recursively remodeled systems for routine bedside assistance and emergency codes. A more focused, effective, customized orientation to the new service space was developed for all staff members, regardless of participation in TESTPILOT. In 2012 and 2013, three other institutions replicated TESTPILOT-NICU with our support. They learned simulation, discovered and corrected latent safety threats, and similarly improved systems readiness and staff preparedness. We hypothesize that other transitioning institutions will benefit from TESTPILOT content and methodology. This prospective study will evaluate whether TESTPILOT is generalizable based on a mixed methods approach with both quantitative and qualitative outcomes: Specific Aim 1: Demonstrate that TESTPILOT quantitatively improves systems readiness and staff preparedness across a spectrum of care delivery structures, simulation experience and magnitudes of culture change. LST discovery is accelerated by relevant scenarios, immersive simulations, and constructive debriefings. LSTs in each institution direct process improvement and training to improve patient safety. Staff reactions are conditioned and recalibrated for the new environment. Institutional improvement trajectory is quantified by surveying clinical experts regarding specific processes before and after NICU transition. Specific Aim 2: Assess saturation of latent safety threats over successive TESTPILOT implementations. LSTs identified in previous TESTPILOTs are openly disseminated in a consortium registry. The classification of LSTs evolves with subsequent implementations. Though novel institution-specific LSTs emerge, we posit a finite universe of novel discoveries. The collection of LSTs that saturates discoveries defines a blueprint for similar transitions. Qualitative outcomes will b based on naturalistic observations on the variation of macrosystems testing given a priori institutional phenotypes. One of the key strengths of TESTPILOT is its ability to uncover safety concerns via human factors using in situ experts. It accomplishes beta testing without live patients. Local experts' systems knowledge is crucial to discovery, more important than previous simulation experience. The local team can readily assimilate the requisite simulation principles: safe environment, in situ, immersive simulation, native roles, progressive simulations, iterative improvement, and prior to move. Unlike previous simulation-based approaches, this study evaluates a process of macrosystems simulation across multiple institutions. To discriminate impact, the qualitative and quantitative measures are NICU-specific. For example, the saturated NICU blueprint would overlap only modestly with an equivalent LST collection for a transitioning Emergency Room. However, the means to optimize LST discovery-the TESTPILOT methodology-is not NICU-specific. We hypothesize the methodology will generalize to other clinical settings and this study will result in a broad blueprint for integrating simulation into oher services in transition.